Joint structure at end of concrete floor slab of bridge

ABSTRACT

A joint structure at an end of a concrete floor slab of a bridge according to an embodiment of the present invention is configured such that: a lowered step part is formed in an upper part of an expansion gap formed between ends of concrete floor slabs or an expansion gap formed between the end of the concrete floor slab and an abutment; joint layers, each made of an elastic asphalt mixture covered with a covering sheet, are formed in the lowered step part; and a paving material is placed on the joint layer to form a surface layer.

BACKGROUND Technical Field

The present invention relates to a joint structure at an end of a concrete floor slab of a bridge such as, for example, a river bridge, a land bridge, and a viaduct.

Generally, as illustrated in FIGS. 1A and 1B, a mainstream joint structure is configured such that a non-connected joint 4 called a finger joint that causes corrugated pates 4 a to engage with each other is buried in an upper part of an expansion gap 3 formed between ends of concrete floor slabs 1, 2 or an expansion gap 3 formed between the end of the concrete floor slab 1 and an abutment 2′, whereby the expansion gap 3 can freely expand and contract within a range of an engagement interval of the corrugated pates 4 a.

However, there is such a problem that the finger joint protrudes from a road surface when concrete around the finger joint is worn, and the protruding finger joint causes noise and vibration due to travelling vehicles.

In this regard, JP 2923586 B1 and JP 2011-162981 A disclose, as a joint structure from which the finger joint is removed, such a structure that a lowered step part is formed in an upper part of an expansion gap formed between ends of concrete floor slabs or an expansion gap formed between the end of the concrete floor slab and an abutment, and a highly stretchable filling material is placed in the lowered step part to form an elastic joint.

More specifically, JP 2923586 B1 and JP 2011-162981 A disclose such a joint structure that the lowered step part is filled with a highly stretchable paving material or highly elastic cement mortar to form an elastic joint part integrated with the end of the concrete floor slab or the abutment, and thus the elastic joint part absorbs expansion and contraction of the expansion gap.

SUMMARY

A highly stretchable paving material or highly elastic cement mortar constituting an elastic joint part of JP 2923586 B1 and JP 2011-162981 A has such a problem that although both the highly stretchable paving material and the highly elastic cement mortar can respond to expansion and contraction of an expansion gap by means of their stretchability and elasticity, a bond between a binder and aggregate is released by repeated loading caused by vehicle travel, whereby the highly stretchable paving material and the highly elastic cement mortar are broken by pressure.

In other words, although each conventional invention employs such a joint structure that the highly stretchable paving material or the highly elastic cement mortar is placed instead of a finger joint, this joint structure contains such a problem that the placed highly stretchable paving material or highly elastic cement mortar is broken by pressure due to the repeated loading.

The present invention does not employ, unlike the above-mentioned conventional bonding joint, such a joint structure that the paving material or the cement mortar is only placed in the lowered step part. Instead, the present invention employs such a joint structure that a joint layer is made of an asphalt mixture confined by a sheet to complement a bond between a binder and aggregate within the asphalt mixture, and this joint layer is arranged in a lowered step part. As a result, a break caused by pressure is effectively prevented.

In summary, the present invention provides a joint structure configured such that: a lowered step part is formed in an upper part of an expansion gap formed between ends of concrete floor slabs or an expansion gap formed between the end of the concrete floor slab and an abutment; a single layer structure or a multilayer structure of a joint layer made of an elastic asphalt mixture covered with a covering sheet is formed in the lowered step part; and a paving material is placed on the joint layer of the single layer structure or an uppermost joint layer of the multilayer structure to form a surface layer. The joint structure configured in this manner flexibly responds to expansion and contraction of the expansion gap and appropriately responds to repeated loading caused by vehicle travel.

Preferably, the asphalt mixture is prepared in such a manner that a main material including butyl rubber or ethylene-propylene rubber and asphalt is heated and melted into a mixture, and the mixture is used as a binder with which known aggregate and filler or the like are mixed. This asphalt mixture is used to form the joint layer that is easily deformed.

As the paving material constituting the surface layer, an asphalt mixture with high elasticity which is the same as the asphalt mixture constituting the joint layer is desirably used.

A surface of the covering sheet serving as an outer surface of the joint layer is an adhesive surface, thereby forming the joint layer that appropriately follows a bottom surface and an inner wall surface of the lowered step part. The adhesive surface is preferably formed of such a mixture that a main material including butyl rubber or ethylene-propylene rubber and asphalt is heated and melted.

A covering surface of the covering sheet that covers the asphalt mixture is a rough surface, whereby bondability to the covered asphalt mixture is improved. The covering surface is preferably formed of a fiber sheet, and fibers constituting the fiber sheet improve the bondability to the asphalt mixture.

The present invention can realize a joint structure that flexibly responds to expansion and contraction of an expansion gap but is not broken by pressure. This joint structure is configured such that a non-connected joint structure including a single layer structure or a multilayer structure of a joint layer made of an asphalt mixture covered with a covering sheet cooperates with a surface layer provided on the non-connected joint structure. The joint structure can be used for a long period of time.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a partially cut perspective view schematically illustrating a pair of concrete floor slabs adjacent to each other via an expansion gap, or a concrete floor slab and an abutment adjacent to each other via an expansion gap in an existing bridge;

FIG. 1B is a cross-sectional view in a bridge length direction illustrating a lowered step part formed in an upper part of the expansion gap;

FIG. 2A is a cross-sectional view in the bridge length direction illustrating a covering sheet laid on a waterproof sheet laid on the lowered step part, and an asphalt mixture placed on the covering sheet;

FIG. 2B is a cross-sectional view in the bridge length direction illustrating the placed asphalt mixture covered with the covering sheet to form a joint layer;

FIG. 3A is a cross-sectional view in the bridge length direction illustrating another covering sheet further laid on the joint layer, and another asphalt mixture placed on the covering sheet;

FIG. 3B is a cross-sectional view in the bridge length direction illustrating the placed asphalt mixture covered with the covering sheet to form two joint layers;

FIG. 4 is a cross-sectional view in the bridge length direction illustrating a joint structure according to an embodiment of the present invention;

FIG. 5 is a cross-sectional view in the bridge length direction illustrating another example of the joint structure according to an embodiment of the present invention;

FIG. 6 is a cross-sectional view in a bridge width direction illustrating the joint structure according to an embodiment of the present invention;

FIG. 7A is a partially cut perspective view illustrating the covering sheet;

FIG. 7B is a cross-sectional view of the same covering sheet;

FIG. 8A is a partially cut perspective view illustrating another example of the covering sheet;

FIG. 8B is a cross-sectional view of the same covering sheet;

FIG. 9A is a partially cut perspective view illustrating another example of the covering sheet; and

FIG. 9B is a cross-sectional view of the same covering sheet.

DETAILED DESCRIPTION

Hereinafter, the best mode of a joint structure at an end of a concrete floor slab of a bridge according to an embodiment of the present invention will be described based on FIGS. 1A to 9B.

<Basic Structure>

A basic structure of the joint structure according to an embodiment of the present invention is as follows. Essentially, as illustrated in FIGS. 4 to 6, a lowered step part 5 is formed in an upper part of an expansion gap 3 formed between ends of concrete floor slabs 1, 2 or an expansion gap 3 formed between the end of the concrete floor slab 1 and an abutment 2′. A multilayer structure of joint layers 8, 9, each made of an elastic asphalt mixture 7 covered with a covering sheet 6, is formed in the lowered step part 5. A paving material is placed on the uppermost joint layer 9 of the multilayer structure to form a surface layer 14.

In the present example, the multilayer structure including the joint layer 8 and the joint layer 9 is described. However, the present invention is not limited to this example, and does not exclude a single layer structure including a single joint layer and a multilayer structure including three or more joint layers In any case, the elastic asphalt mixture 7 is covered with the covering sheet 6 to form a joint layer structure, and the joint layer structure appropriately responds to expansion and contraction of the expansion gap 3. Hereinafter, a detailed explanation will be provided step by step.

FIG. 1A is a partially cut perspective view schematically illustrating a finger joint buried in the upper part of the expansion gap 3 formed between the ends of the concrete floor slabs 1, 2 or the expansion gap 3 formed between the end of the concrete floor slab 1 and the abutment 2′ in an existing bridge. The finger joint is a non-connected joint. In the drawing, 15 is a pavement part formed on the concrete floor slabs 1, 2 or the abutment 2′. The pavement part 15 is formed of a paving material such as an asphalt mixture.

When the joint structure according to an embodiment of the present invention is implemented in the existing bridge, first, the finger joint 4 is removed together with surrounding concrete on an attachment part. Then, as illustrated in FIG. 1B, the lowered step part 5 is formed in the upper part of the expansion gap 3.

When the joint structure according to an embodiment of the present invention is implemented in a new bridge, as illustrated in FIG. 1B, the lowered step parts 5 are preliminarily formed in upper parts of the ends of the concrete floor slabs 1, 2 or respective upper parts of the end of the concrete floor slab 1 and the abutment 2′. Alternatively, the upper parts of the ends of the concrete floor slabs 1, 2 or the respective upper parts of the end of the concrete floor slab 1 and the abutment 2′ are scraped on site to form the lowered step parts 5.

The concrete floor slabs 1, 2 as used in the present application include all of the following floor slabs: a concrete floor slab molded from site-cast concrete; a PC concrete floor slab molded in a factory; or a floor slab made of concrete in a composite bridge or the like molded from a steel girder (e.g., H-shaped steel girder) and a placed concrete floor slab or a PC concrete floor slab.

Next, as illustrated in FIG. 2A, a waterproof sheet 16 is laid on a bottom surface 5 a of the lowered step part 5. A part of the waterproof sheet 16 is suspended into the expansion gap 3 to form a suspended part 16 c. The suspended part 16 c appropriately prevents rainwater or the like from intruding into the expansion gap 3. In particular, the suspended part 16 c appropriately prevents rising surfaces 1 a, 2 a at the ends of the concrete floor slabs 1, 2 or a rising surface 2′a of the abutment 2′ constituting the expansion gap 3 from being exposed to rainwater or the like.

Then, the covering sheet 6 is laid on the waterproof sheet 16, and the elastic asphalt mixture 7 is placed on the covering sheet 6. Furthermore, as illustrated in FIG. 2B, free end parts 6 c, 6 d of the covering sheet 6 are folded back on the placed asphalt mixture 7 so as to overlap each other. The placed asphalt mixture 7 is thus covered with the covering sheet 6 and hardened to form the joint layer 8 in the lowered step part 5.

As described later, the covering sheet 6 is configured such that one surface 6 a serving as an outer surface 8 a of the joint layer 8 is an adhesive surface, and the other surface 6 b that covers the asphalt mixture 7 is a rough surface. The one surface 6 a, i.e., the adhesive surface, comes into close contact with a front surface 16 b of the waterproof sheet 16 laid on the bottom surface 5 a of the lowered step part 5, and the other surface 6 b, i.e., the rough surface, is firmly bonded to the asphalt mixture to be covered, whereby the joint layer 8 is formed. Since the free end parts 6 c, 6 d of the covering sheet 6 overlap each other to cover the asphalt mixture 7, the one surface 6 a, i.e., the adhesive surface, of either one of the free end parts 6 c, 6 d adheres to the other surface 6 b, i.e., the rough surface, of the other one of the free end parts 6 c, 6 d, whereby the asphalt mixture 7 is securely covered.

As illustrated in FIG. 6, left and right end parts in a bridge width direction of the joint layer 8 are covered with end part covering sheets 6′ having the same configuration as the covering sheet 6, whereby the asphalt mixture 7 is appropriately prevented from flowing out. The present example has described such a configuration that the left and right end parts in the bridge width direction of the joint layer 8 are covered with the end part covering sheets 6′. However, the present invention is not limited this example, and does not exclude, for example, such a configuration that the asphalt mixture 7 is covered with the covering sheet 6 having folding margins both in a bridge length direction and the bridge width direction to form the joint layer 8.

In the present example, as illustrated in FIG. 3A, the new covering sheet 6 is further laid on the joint layer 8, and the elastic asphalt mixture 7 is placed on the covering sheet 6 in the same way as the joint layer 8. As illustrated in FIG. 3B, the placed asphalt mixture 7 is covered, whereby the joint layer 9 is put on the joint layer 8 in a multilayered manner. Each of the outer surface 8 a of the joint layer 8 and an outer surface 9 a of the joint layer 9 includes the adhesive surface 6 a of the covering sheet 6. The outer surfaces 8 a, 9 a come into close contact with each other in a vertical direction. Since a configuration of the joint layer 9 is the same as that of the aforementioned joint layer 8, a description thereof is omitted.

Finally, as illustrated in FIG. 4, the paving material is placed on the joint layer 9 to form the surface layer 14. The surface layer 14 is integrated with the pavement part 15 formed on the concrete floor slabs 1, 2 or the abutment 2′. The paving material constituting the surface layer 14 is desirably formed using an asphalt mixture which is the same as the asphalt mixture 7 constituting each of the joint layers 8, 9 so that the surface layer 14 follows deformation of the joint layers 8, 9 and thus is deformed.

FIG. 5 is a view illustrating another example of the joint structure without the waterproof sheet 16 according to an embodiment of the present invention.

Specifically, the illustrated exemplary structure is configured such that the covering sheet 6 is directly laid on the bottom surface 5 a of the lowered step part 5 to form the aforementioned joint layer 8, the aforementioned joint layer 9 is formed on the joint layer 8, and the surface layer 14 is formed on the joint layer 9.

In this exemplary structure, preferably, when the covering sheet 6 is laid in the lowered step part 5, a part of the covering sheet 6 is suspended into the expansion gap 3 to form a suspended part 6 e, and the asphalt mixture 7 is placed in the suspended part 6 e as well and hardened to form a projection part 8 b in the joint layer 8. The projection part 8 b appropriately prevents rainwater or the like from intruding into the expansion gap 3. In particular, the projection part 8 b appropriately prevents the rising surfaces 1 a, 2 a at the ends of the concrete floor slabs 1, 2 or the rising surface 2′a of the abutment 2′ constituting the expansion gap 3 from being exposed to rainwater or the like.

As described above, the joint structure according to an embodiment of the present invention is configured such that the elastic asphalt mixture 7 is confined by the covering sheet 6, whereby the joint layers 8, 9 are provided in the lowered step part 5. Each of the joint layers 8, 9 complements a bond between a binder and aggregate within the asphalt mixture 7 by means of the covering sheet 6 and appropriately absorbs expansion and contraction of the expansion gap 3. The joint layers 8, 9 cooperate with the surface layer 14 to produce the joint structure that appropriately responds to expansion and contraction of the expansion gap 3 but does not hinder vehicle travel.

<Asphalt Mixture 7>

Hereinafter, the elastic asphalt mixture 7 constituting each of the aforementioned joint layers 8, 9 will be described. The asphalt mixture 7 is preferably prepared in such a manner that a main material including butyl rubber or ethylene-propylene rubber and asphalt is heated and melted into a mixture, and the mixture is used as a binder with which known aggregate and filler or the like are mixed. This asphalt mixture is used to form each of the elastic joint layers 8, 9 that is easily deformed. Process oil is added to the binder as necessary.

Preferable combination examples of the asphalt mixture 7 are as follows. A combination ratio of a binder (mixture of a main material including butyl rubber or ethylene-propylene rubber and asphalt) to aggregate is 26-2:74-98 in weight ratio.

Combination Example 1

butyl rubber or ethylene-propylene rubber 20-200 kg/m³ process oil 10-100 kg/m³ asphalt 20-200 kg/m³ aggregate (sand and gravel) 1400-2400 kg/m³  

Combination Example 2

butyl rubber or ethylene-propylene rubber 25-250 kg/m³ asphalt 25-250 kg/m³ aggregate (sand and gravel) 1400-2400 kg/m³  

In the present invention, as described above, the asphalt mixture 7 is desirably used as the paving material constituting the surface layer 14 to form the surface layer 14 that follows the deformation of the joint layers 8, 9. Since the formation of the surface layer 14 is limited to a part on the joint layer, the surface layer 14 can be easily removed and easily renewed even if the surface layer is deteriorated over time.

<Covering Sheet 6 (End Part Covering Sheet 6′) and Waterproof Sheet 16>

As illustrated in FIGS. 7A and 7B, the covering sheet 6 according to an embodiment of the present invention is configured such that the one surface 6 a serving as each of the outer surfaces 8 a, 9 a of the joint layers 8, 9 is the adhesive surface, and the other surface 6 b that covers the asphalt mixture 7 is the rough surface. The one surface 6 a, i.e., the adhesive surface, comes into close contact with the bottom surface 5 a and a side surface 5 b of the lowered step part 5 or the front surface 16 b of the waterproof sheet 16, and the other surface 6 b, i.e., the rough surface, is firmly bonded to the asphalt mixture 7 to be covered.

The adhesive surface 6 a is formed of an adhesive material 10. For example, in the same way as the binder of the asphalt mixture 7, a main material including butyl rubber or ethylene-propylene rubber and asphalt is heated and melted into a mixture, and the adhesive surface 6 a is formed of the adhesive material 10 including this mixture. Since the adhesive material 10 is soft and easily deformed, a mesh sheet 11 is desirably buried in the mixture to maintain the shape of the adhesive material 10 and reinforce the adhesive material 10. The mesh sheet 11 is knitted out of a known aramid fiber, nylon fiber, and carbon fiber or the like.

The other surface 6 b serving as a covering surface of the covering sheet 6 is formed of a fiber sheet 12 as the rough surface. For example, the fiber sheet 12 is formed of a nonwoven fabric. Fibers constituting the fiber sheet 12 are buried in the asphalt mixture 7, and a gap between the fibers of the fiber sheet 12 is impregnated with components of the asphalt mixture 7, whereby the fiber sheet 12 and the asphalt mixture 7 are firmly bonded together.

In addition, in order to prevent the fiber sheet 12 from being impregnated with the adhesive material 10, a synthetic resin sheet 13 including a synthetic resin such as polyvinyl chloride is arranged between the fiber sheet 12 and the adhesive material 10.

An undercoating agent is applied to the other surface (rough surface) 6 b of the covering sheet 6 to perform primer treatment as necessary, whereby the bond to the asphalt mixture 7 and the adhesion between the free end parts 6 c, 6 d are further strengthened. As the undercoating agent, such a mixture that a main material including butyl rubber or ethylene-propylene rubber and asphalt is heated and melted is desirably used. In other words, a liquid containing components which are the same as those of the binder within the asphalt mixture 7 is desirably used as the undercoating agent. A known organic paint is optionally used as the undercoating agent depending on the implementation.

The end part covering sheets 6′ used for the left and right end parts in the bridge width direction of the joint layers 8, 9 are configured in the same way as the covering sheet 6.

A sheet having the same configuration as the covering sheet 6 is desirably used for the waterproof sheet 16 as well. In this case, a back surface 16 a of the waterproof sheet 16 is an adhesive surface, and the front surface 16 b of the waterproof sheet 16 is a rough surface. The back surface 16 a is brought into close contact with the bottom surface 5 a of the lowered step part 5 along an uneven shape of the bottom surface 5 a, and the front surface 16 b is securely brought into close contact with the outer surface 8 a (one surface 6 a of the covering sheet 6) of the joint layer 8.

FIGS. 8A, 8B, 9A, and 9B are views illustrating other examples of the covering sheet 6. The covering sheet 6 illustrated in FIGS. 8A and 8B includes the adhesive material 10 and the mesh sheet 11 buried in the adhesive material 10. The other surface 6 b is not a rough surface unlike the covering sheet 6 illustrated in FIGS. 7A and 7B, but an adhesive surface like the one surface 6 a. The covering sheet 6 illustrated in FIGS. 9A and 9B includes the adhesive material 10, the mesh sheet 11 buried in the adhesive material 10, and the synthetic resin sheet 13 kept in close contact with the adhesive material 10. The other surface 6 b is not a rough surface unlike the covering sheet illustrated in FIGS. 7A and 7B, but formed of the synthetic resin sheet 13. In any case, each of the covering sheets 6 in these examples has the one surface 6 a serving as the adhesive surface. The one surface 6 a comes into close contact with the bottom surface 5 a and the side surface 5 b of the lowered step part 5 and constitutes each of the outer surfaces 8 a, 9 a of the joint layers 8, 9, thereby bringing the joint layers 8, 9 into close contact with each other.

Needless to say, sheets having the same configuration as the covering sheets 6 in the examples of FIGS. 8A, 8B, 9A, and 9B can be used as the end part covering sheet 6′ and the waterproof sheet 16.

As described above, the joint structure according to an embodiment of the present invention is configured such that each of the joint layers 8, 9 is formed of the elastic asphalt mixture 7 covered with the covering sheet 6, the surface layer 14 is also formed of the elastic asphalt mixture 7 on the joint layer 9 and integrated with the pavement part 15, and the joint layers 8, 9 can cooperate with the surface layer 14 to appropriately respond to expansion and contraction of the expansion gap 3.

More specifically, while each of the joint layers 8, 9 has the elasticity and flexibility owing to the asphalt mixture 7 constituting each of the joint layers 8, 9, it is covered with the covering sheet 6. Therefore, the deformation of the joint layers 8, 9 is restricted to some extent by the covering sheet 6, and particularly by the mesh sheet 11 within the adhesive material 10, the fiber sheet 12, and the synthetic resin sheet 13 constituting the covering sheet 6.

Consequently, when the expansion gap 3 is widened, each of the joint layers 8, 9 is slightly reduced in thickness as compared with a normal state and extended in the bridge length direction. To the contrary, when the expansion gap 3 is narrowed, each of the joint layers 8, 9 is slightly increased in thickness as compared with the normal state and shrunk in the bridge length direction. In this way, the joint layers 8, 9 appropriately join the concrete floor slabs 1, 2 together or join the concrete floor slab 1 to the abutment 2′ while absorbing expansion and contraction of the expansion gap 3.

Since the asphalt mixture 7 constituting each of the joint layers 8, 9 is confined by the covering sheet 6, the bond between the binder and the aggregate within the asphalt mixture 7 is complemented. As a result, the joint layers 8, 9 are not broken by pressure and can be used as a joint for a long period of time.

The surface layer 14 itself has the elasticity and follows the deformation of the joint layers 8, 9.

In the present application, a numerical range indicating lower and upper limits with “-” represents all the numerical values (integer values and fractional values) between the lower limit and the upper limit. 

1. A joint structure at an end of a concrete floor slab of a bridge, wherein a lowered step part is formed in an upper part of an expansion gap formed between ends of concrete floor slabs or an expansion gap formed between the end of the concrete floor slab and an abutment, a single layer structure or a multilayer structure of a joint layer made of an elastic asphalt mixture covered with a covering sheet is formed in the lowered step part, and a paving material is placed on the joint layer of the single layer structure or an uppermost joint layer of the multilayer structure to form a surface layer.
 2. The joint structure at an end of a concrete floor slab of a bridge according to claim 1, wherein the asphalt mixture is such an asphalt mixture that a main material including butyl rubber or ethylene-propylene rubber and asphalt is heated and melted into a mixture, and the mixture is used as a binder.
 3. The joint structure at an end of a concrete floor slab of a bridge according to claim 1, wherein an asphalt mixture which is the same as the asphalt mixture constituting the joint layer is used as the paving material constituting the surface layer.
 4. The joint structure at an end of a concrete floor slab of a bridge according to claim 1, wherein a surface of the covering sheet serving as an outer surface of the joint layer is an adhesive surface.
 5. The joint structure at an end of a concrete floor slab of a bridge according to claim 4, wherein the adhesive surface of the covering sheet is formed of such a mixture that a main material including butyl rubber or ethylene-propylene rubber and asphalt is heated and melted.
 6. The joint structure at an end of a concrete floor slab of a bridge according to claim 1, wherein a covering surface of the covering sheet that covers the asphalt mixture is a rough surface.
 7. The joint structure at an end of a concrete floor slab of a bridge according to claim 6, wherein the covering surface of the covering sheet is formed of a fiber sheet.
 8. The joint structure at an end of a concrete floor slab of a bridge according to claim 2, wherein an asphalt mixture which is the same as the asphalt mixture constituting the joint layer is used as the paving material constituting the surface layer.
 9. The joint structure at an end of a concrete floor slab of a bridge according to claim 2, wherein a surface of the covering sheet serving as an outer surface of the joint layer is an adhesive surface.
 10. The joint structure at an end of a concrete floor slab of a bridge according to claim 3, wherein a surface of the covering sheet serving as an outer surface of the joint layer is an adhesive surface.
 11. The joint structure at an end of a concrete floor slab of a bridge according to claim 2, wherein a covering surface of the covering sheet that covers the asphalt mixture is a rough surface.
 12. The joint structure at an end of a concrete floor slab of a bridge according to claim 3, wherein a covering surface of the covering sheet that covers the asphalt mixture is a rough surface.
 13. The joint structure at an end of a concrete floor slab of a bridge according to claim 4, wherein a covering surface of the covering sheet that covers the asphalt mixture is a rough surface.
 14. The joint structure at an end of a concrete floor slab of a bridge according to claim 5, wherein a covering surface of the covering sheet that covers the asphalt mixture is a rough surface. 